Search found 608 matches

by KenLowe
Mon Aug 12, 2019 1:09 pm
Forum: hardware
Topic: B or upgraded A? Version 7. Upgrade Advice??
Replies: 22
Views: 668

Re: B or upgraded A? Version 7. Upgrade Advice??

Ken, I was going to say that the 1K column in the truth table should have some don't cares but then I notice that the 4K column overlaps with the 1K section: Control bits Memory pages and selected area PRVEN | PRVS1 from &8000 &8000 &9000 &B000 | | PRVS4 | | | PRVS8 to &83FF &8FFF &AFFF &BFFF | | |...
by KenLowe
Mon Aug 12, 2019 5:00 am
Forum: hardware
Topic: B or upgraded A? Version 7. Upgrade Advice??
Replies: 22
Views: 668

Re: B or upgraded A? Version 7. Upgrade Advice??

I have been reading the Integra B user guide, which seems to have many similarilties with the Master but this must be a later revision because I am sure the Integra B came out before the master, unless I am confusing it with something else. I think the IntegraB came out around 1987 (see this photo ...
by KenLowe
Mon Aug 12, 2019 4:35 am
Forum: hardware
Topic: B or upgraded A? Version 7. Upgrade Advice??
Replies: 22
Views: 668

Re: B or upgraded A? Version 7. Upgrade Advice??

Ken, there is discrepancy between the extra from the manual you have pasted into the thread here and the OCR version of the manual you have uploaded to 8bs. The 8bs RTF version has the private RAM bits of FE34 as: bit6 PRVS8 - 8K from &9000-&AFFF bit5 PRVS4 - 4K from &8000-&8FFF bit4 PTVS1 - 1K fro...
by KenLowe
Sun Aug 11, 2019 6:50 pm
Forum: hardware
Topic: B or upgraded A? Version 7. Upgrade Advice??
Replies: 22
Views: 668

Re: B or upgraded A? Version 7. Upgrade Advice??

The IntegraB board includes a 32k RAM module for Shadow RAM. As with the BBC+, only 20k is required to shadow the screen, so 12k is available for other uses. The IntegraB OS uses a small bit of this for storing some IntegraB variables, and the rest is available as 'Private RAM'... This does seem ve...
by KenLowe
Sun Aug 11, 2019 6:59 am
Forum: hardware
Topic: B or upgraded A? Version 7. Upgrade Advice??
Replies: 22
Views: 668

Re: B or upgraded A? Version 7. Upgrade Advice??

is there anything else I should consider (is there any way to upgrade to a B+ 64/128 at all)? Apart from the sideways RAM (in the B+128K) the other main feature of the B+ was shadow screen memory. KenLowe has developed a board which is almost a remake of a Integra B which I believe includes some sh...
by KenLowe
Sat Aug 10, 2019 12:20 pm
Forum: hardware
Topic: Will a BBC Master 128 PSU work in a BBC model B issue 7?
Replies: 13
Views: 305

Re: Will a BBC Master 128 PSU work in a BBC model B issue 7?

I've also inadvertently tested on an issue 4 board by forgetting to connect one set of leads (the ones nearest the PSU) onto the board with no adverse effect!
by KenLowe
Sat Aug 10, 2019 9:14 am
Forum: hardware
Topic: Will a BBC Master 128 PSU work in a BBC model B issue 7?
Replies: 13
Views: 305

Re: Will a BBC Master 128 PSU work in a BBC model B issue 7?

I'm guessing there must have been some linkage between the 3 supplies? At the very least, I assume the 0v rails were commoned together to get a common reference? And then various signals would need to pass between the 3 isolated systems? I assume there was no opto isolation between those systems?
by KenLowe
Fri Aug 09, 2019 12:06 pm
Forum: hardware
Topic: Mystery card in BBC B from ebay
Replies: 9
Views: 335

Re: Mystery card in BBC B from ebay

J21 (S21?) is actually a group of 4 pins, and two jumpers need to be used on these pins. The jumpers can run North to South or East to West. If removing the expansion board, then one jumper should connect pin NE to pin NW and the other jumper should connect pin SE to pin SW. The jumper between NE an...
by KenLowe
Tue Jul 23, 2019 12:07 pm
Forum: hardware
Topic: BBC Model B - Issue 7 problem - Solved
Replies: 67
Views: 1370

Re: BBC Model B - Issue 7 problem

If the motor relay is permanently energised and the LED is permanently lit, then I would have a look at transistor Q3 (BC239) as this is what drives both the relay and the LED. Also worth checking IC7 pin 11 to see if this changes state as you try to toggle the relay. Also check flyback diode D13 is...
by KenLowe
Sun Jul 21, 2019 2:46 pm
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 93
Views: 3864

Re: New ROM / RAM Expansion Board for BBC B

For those who have been following this thread, but not my For Sale thread, please be advised that I have built a new batch of boards with an up-revved PCB, eliminating the routing errors picked up in the first batch. There are also a number of other minor layout improvement over the first batch. Det...
by KenLowe
Sun Jul 21, 2019 2:34 pm
Forum: for sale / freebies
Topic: New Batch ROM / RAM Expansion Board for BBC B
Replies: 2
Views: 374

Re: New Batch ROM / RAM Expansion Board for BBC B

That's a small batch completely built up and ready to ship. The most time consuming bit is getting all the 'extras' sorted! The observant amongst you might have spotted that some of the packages are missing the 40 pin extender. I'm just waiting for a new batch to arrive. Hopefully they'll be here ea...
by KenLowe
Mon Jul 15, 2019 10:46 pm
Forum: emulators
Topic: Unreleased Android version of B-Em
Replies: 8
Views: 641

Re: Unreleased Android version of B-Em

This is awesome. Successfully installed on my Galaxy S7 Edge. It stuck at 'Initialising' for a bit on first startup, but subsequent start ups are a lot faster. Haven't done much with it yet, other than get to the > prompt. Time to dig out some disk images... Edit: Just found the 'Local discs'. Brill...
by KenLowe
Sun Jul 14, 2019 10:38 pm
Forum: hardware
Topic: Page ROM/RAM
Replies: 28
Views: 1087

Re: Page ROM/RAM

Have you had a look at the reference guide? http://ee-classes.usc.edu/ee459/library/documents/CUPL_Reference.pdf Most of my experience is with the GAL22V10 & GAL16V8. With these devices, pin 1 is defined as the clock pin when the pld is being used in 'registered' mode. I'm guessing the PLD that you'...
by KenLowe
Sun Jul 14, 2019 10:51 am
Forum: hardware
Topic: Page ROM/RAM
Replies: 28
Views: 1087

Re: Page ROM/RAM

Also, good call on the Advanced ROM Manager (ARM) as I've never used it before. As you say, the *REX command makes life so much easier. I did find one issue with it though: When I was testing it within Beebem it had a habit of overwriting rom copyright string in sideways RAM after a restart. So (C)...
by KenLowe
Sat Jul 13, 2019 9:56 pm
Forum: hardware
Topic: Page ROM/RAM
Replies: 28
Views: 1087

Re: Page ROM/RAM

Looks like you're making good progress. For info, my IntegraB board generates /WDS and /RDS signals, and these feed into the /WE and /OE inputs of my RAM (62256 in my case): nRDS.PNG RAM.PNG Where PHI1 comes from 6502 pin 3, and RnW comes from 6502 pin 34. The rb4_5 & rb6_7 signals come from a 4 / 1...
by KenLowe
Wed Jul 10, 2019 9:35 pm
Forum: for sale / freebies
Topic: New Batch ROM / RAM Expansion Board for BBC B
Replies: 2
Views: 374

Re: New Batch ROM / RAM Expansion Board for BBC B

Sorry for the bump. I tried to edit my earlier post to add an updated User Guide, but I think there must be a limit to the number of attachments I can add to an individual post. Updated User Guide attached here...
by KenLowe
Sun Jul 07, 2019 7:43 pm
Forum: off-topic
Topic: Faulty car radio
Replies: 5
Views: 408

Re: Faulty car radio

Oh. That's interesting. I always thought the quadlock connector was the much larger square connector that takes the power, speaker and various other signals from the car to the radio. This odd 13 pin connector runs between the Connects2 Canbus interface and the head unit. A wider quadlock search sti...
by KenLowe
Sun Jul 07, 2019 3:41 pm
Forum: for sale / freebies
Topic: New Batch ROM / RAM Expansion Board for BBC B
Replies: 2
Views: 374

New Batch ROM / RAM Expansion Board for BBC B

Hi, I've had a few requests from various sources for a second batch of IntegraB boards, so I ordered up another small quantity of PCBs and built these up over the last few weeks. The routing errors that were in my first batch have been fixed on these boards. I'm primarily selling these new boards vi...
by KenLowe
Sat Jul 06, 2019 9:25 am
Forum: off-topic
Topic: Faulty car radio
Replies: 5
Views: 408

Faulty car radio

I've got a faulty after market AVIC-EVO1-PL2-VAL Pioneer car radio, and I think I've narrowed the fault down to the canbus interface unit that picks up various signals from the bus, and outputs them as hard wired signals to the radio (accessory switch, light switch, reverse, speed pick up etc). The ...
by KenLowe
Sat Jun 29, 2019 10:03 am
Forum: hardware
Topic: Trouble formatting a floppy .dsd on my Gotek
Replies: 13
Views: 399

Re: Trouble formatting a floppy .dsd on my Gotek

If you don't have a a format utility on disk or ROM, then it will be difficult to format a disk (you can do it, you just need to type in a program or load from tape as I suggested earlier). The delete function is an integral utility on the DFS ROM, so you will be able to delete files without needing...
by KenLowe
Sat Jun 29, 2019 9:39 am
Forum: hardware
Topic: Trouble formatting a floppy .dsd on my Gotek
Replies: 13
Views: 399

Re: Trouble formatting a floppy .dsd on my Gotek

Yes. A real floppy drive will work in exactly the same way, but in fact might be a little bit more difficult for you format a disk, since you need to either type in a formatting program on the beeb (or load from tape), or already have a disk / utility ROM with the formatting software on it. With the...
by KenLowe
Sat Jun 29, 2019 9:18 am
Forum: hardware
Topic: Trouble formatting a floppy .dsd on my Gotek
Replies: 13
Views: 399

Re: Trouble formatting a floppy .dsd on my Gotek

Ok. Download this: https://stardot.org.uk/forums/download/file.php?id=8351 Unzip, and copy the .ssd file over to the USB stick you're using in your GoTek. Select this disk on your GoTek using the rotary knob or buttons on the GoTek, and press Shift-Break on the beeb to boot the disk. Select Option O...
by KenLowe
Sat Jun 29, 2019 8:41 am
Forum: hardware
Topic: Trouble formatting a floppy .dsd on my Gotek
Replies: 13
Views: 399

Re: Trouble formatting a floppy .dsd on my Gotek

No. It doesn't matter what revision of board you have. You need to get hold of some formatting software, either on a utility ROM or on disk. I'm sure there's a ssd disk image on this board with the necessary software that you could copy over to your GoTek. You could then run this software and switch...
by KenLowe
Sun Jun 23, 2019 7:16 am
Forum: hardware
Topic: Proposed: "The Ultimate Electron Upgrade"
Replies: 447
Views: 29085

Re: Proposed: "The Ultimate Electron Upgrade"

Wow. Super impressive. Well done. =D> =D> =D>
by KenLowe
Sun Jun 23, 2019 7:10 am
Forum: hardware
Topic: Do I need a ROM to attach a disk drive ?
Replies: 6
Views: 259

Re: Do I need a ROM to attach a disk drive ?

dougal22 wrote:
Sun Jun 23, 2019 7:03 am
No the socket is empty.
In that case, you will need additional hardware. It's quite difficult to get hold of the older 8271 hardware, but a couple of ebay vendors sell the 1770 upgrade kits for approx. £25 / £30.
by KenLowe
Sun Jun 23, 2019 6:59 am
Forum: hardware
Topic: Do I need a ROM to attach a disk drive ?
Replies: 6
Views: 259

Re: Do I need a ROM to attach a disk drive ?

Yes, you will need an extra ROM, but you need a floppy disk controller and some glue logic in your BBC as well. The ROM you install will depend on the floppy disk controller you've got. The floppy disk controller (typically a 8271 or 1770) plugs into IC78. Do you currently have anything plugged into...
by KenLowe
Wed Jun 19, 2019 10:53 pm
Forum: hardware
Topic: What's In My Beeb?
Replies: 33
Views: 1131

Re: What's In My Beeb?

tricky wrote:
Wed Jun 19, 2019 10:30 pm
I've never seen that design of ROM board before.
I'm loving the routing of the tracks on that board :shock:
by KenLowe
Wed Jun 19, 2019 7:41 pm
Forum: hardware
Topic: Model B ROM Board
Replies: 10
Views: 437

Re: Model B ROM Board

That one wire is enough. From the looks of things it goes to S21 (south-west), where it controls the gate on IC20, part of the mainboard's ROM selection circuitry. IC76 will be storing and latching the lower two bits of every write to the /ROMSEL address, as it normally does, but with the modificat...
by KenLowe
Wed Jun 19, 2019 3:00 pm
Forum: hardware
Topic: Model B ROM Board
Replies: 10
Views: 437

Re: Model B ROM Board

The 6502 processor seems to be missing altogether, but I guess it's hidden under the ribbon cable? Difficult to see from the photo. Assuming the 6502 is there somewhere, then it looks like the board is picking up and buffering address and data lines from the 6502. The larger IC on the board looks to...